Lifting jack



T. Fi. HOLLAND vLIFTING JACK A :Fiared'mamh 14.4923

Q n m I N VEN TOR.

7.7/12 .f5/a Hama! l B Y A i Y I.

'ATTORAEY Patented Oct. 21, 1924.

THOMAS n. HOLLAND, or wnNAror-rnn, WASHINGTON.

LIFTING JACK.

Application le'd March 14, 1923. Serial No; 625,109.

T all whom t may concern:

Be it known that I, THOMAS R. I-IOLLAND, a citizen of the United States, residing at Wenatchee, in the county of Ohelan and State of Washington, have invented certain new and useful Improvements in Lifting Jacks, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to lifting jacks, and the object of the invention is to provide a lifting jack which is operated without the use of dogs, pawls or like devices and which may be, therefore, lifted or lowered to a very slight degree and adjusted exactly to any height desired.

A further object is to provide a construc. tion of this character wherein the jack is raised by means of a friction clutch and is held in a raised position by a coacting friction clutch, the last named friction clutch having means whereby it may be expanded to exert greater or less friction upon the movable member of the clutch to thus permit the jack to be llowered at a more or less rapid rate under the weight of the object.

Other objects have to do with the details of construction and arrangement of parts as will appear more fully hereinafter.

My invention is illustrated in the accompanying drawings, wherein Figure 1 is a. side elevation of a lifting jack constructed in accordance with my invention;

Figure 2 is an end elevation thereof;

Figure 3 is another side elevation opposite to the elevation shown in Figure 1, showing in dotted lines the rack and gear connection' Referring to these drawings,10 designates the body of the jack, having the usual base or foot 11 formed integral with the body and the body being reinforced by the vertical ribs 12. Operating within the body is the vertically adjustable standard 13, provided with a head 14 at its upper end formed to fit beneath the object to be lifted, this standard 13 being formed with gear teeth 15.

Passing through the body or mounted thereon in any suitable manner is a shaft '16, which shaft carries upon it the gear wheel 17 which engages the teeth 15 and which gear wheel projects out through an opening 18 in the side wall of the body 1,0. For the purpose of operating upon it the gear wheel 17 and thereby operating the standard 15, I mount upon the shaft 16 a friction drum 419 and operating in conjunction with this drum is the sectional friction band composed, as shown, of the two sections 2O and 21, the-se sections being pivoted to each other at 22. The section 2O is longer than the section 21 and its terminal end 23 extends tangentially to the circumference ofthe drum, and, as before remarked, projects beyond the adjacent extremity of the section 21. Y

Pivoted to the section 21 at 211 is an operating lever 25 and the extremity v23 of the section 2() is also pivoted to this operating lever at 26. As illustrated, the extremity of the section 21 is the upper edge of the lever 25 is formed with spaced ears between which the extremity of the section 2O is disposed, the pin 26 `passing through these ears and through thev section 20. Inasmuch as the section 23. is pivoted to the lever 25 outward -of the pivotal point 241, it is obvious that upon a depression of the free end of the lever 25 the two lsections of the friction band will be drawn together and have very tight frictional engagement with the drum 19. Preferably Ya coiled contractilel spring 27 vis engaged with the section 2O inward' of its point of pivotal engagement 26 with the lever 25, and the other end of this lever 27 is engaged with the inner end of the lever 25. A stop' lug .28 is carried by the body 10 and projects out in the path of movement of the lever 25 and constitutes a stop for this lever when drawn in one direction.. Obviously when the lever 25 is drawn upward so as to engage against the stop 28, the two sections of the band will be fully opened and the drum will be entirely free. Ontthe other hand, when the lever 25 is drawn downward, the sections of the band will' be clamped upon the drum and will frictionally engage, the same so as to clutch the drum to the lever. Preferably the two sections 2() and 21 of the band are pivotally connected by a. pin 22. j

The opposite end of the shaft 16 carries a friction drum 29 and extending around this friction drum 29 is a two-section brakeband, one of thc sections being-desigbifurcated to receive Vthe end of the operating lever 25, while nated 30 and the other 31. The sectionsBO all .crurned upon the stop at its end opposite the connection 32 is formed with an ear 33 pivoted by a pin 3a to a lever This lever 35 is pivoted at 36 to the body l0. The section 3l of the band embraces a portion of the periphery of the drum, then extend tangent-hilly downward and toward the lever and is pivoted by pin 37 to this lever 55a this point of pivotal connection being beyond the point of pivotal connection of the section 30 te the lever. c'ilied compression spring 38 supported at one end in any suitable manner hearsagainst the upper eno of the lever and urges it outward. i

Pivotally mounted upon the body l is cam 39 having a handle 40.' This cani is eccentricallyr pivoted upon a pin el. and when this cani is turned so as to cause it to bear against' thelever 35 it will force the upper end of the lever 35 inward, thus reducing or breaking the frictional Contact between the brake band formed of the sections 3 and 3l and the friction wheel or drum 2't lflhen7 however7 the' handle l0 is lowered to the position shown in Figure l, the spring 3S will act upon the lever 35 to cause the sections of the brake band to bind upon and frictionally lock on the drum 29. lt will be noted from Figure 3v that as the handle 25 is raised, assuming there is a weight on the standard, the handle 25 and the clutch mei' bers 20 and 2l will nieve with the drum 19 in a clockwise direction. When, however, the handle end olif the clutch section 2O engages the stop 23, the stop 28 as a fulcrum for the levei` 25 and permits this lever to be still further lifted, and this further lifting movement will act to open or separate the clutch sections and 2l, thus permitting the. standard 13 to move downward andk permitting the rotation of the drinn 19 within the clutch sections7 the speed of this rotation of the drum lf) being governed the frictional resistance of the bands 20' and 2l. yllhus if the outer end of the lever is lifted when the lever is fnl- 28, the slut-ca sections will be entirely opened,y but is desired to check the downward noveinent of the standard; the lever 25 is l,epressed slightly7 whichy will camel the clutch sections to contract upon the drum thus applying frictional resistance thereto;V

llVit-h the friction clutch in the position shewn'in lFigures aiid 3 and the cani handle 40 down7 the standard or rack l5 is raised by alternately lowering and raising the handle 25 until the standard is at the desi ed height. New in oider'to lower the standa dthe pressure en the head le is entirely taken orv by pressing down on the liaridle- 25.-The handle of cani l-O is then raised until the frictional engagement betweengd-r'um' 29 andv the hands 30 3l is entirely relieved and then the handle 25 is raised until it comes in contact with stop 28, thus gradually lowering the standard, and when the handle 25 cornes in Contact with the stop 28 a further upward pressure on the hanele against the' stop 28 will cause the bands 2O and 2l to open and the standard will slide down at the will of the operator and controlled by the friction of the bands 20 and 2l against the drum 19.

lt will be seen that this construction gives continuous control of the load in letting the jaclr down and the load may be lifted or lowered to the slightest fraction of an inch', as there are no dogs or pawls which can only engage at predetermined points. The fricti ti clutch or brale formed by the sections and 3l of the drum 29 acts immediately/to hold the rack bar or standard from c'lepresF sion and by operating the cani 39 any desired degree of frictional resistance to the lo ering of the load may be secured.

llhile l have illustrated a form of my invention which l deem to be particularly practical, which is Compact and simple, yet it is obvious that the invention might be embodied in other forms without departing from the spirit thereof as defined in the appended claims.

l. A lifting jack of the character de- `ibed comprising a tubular base', a stand'- l movable vertically within the basea the rd having ralelr teeth, ai gear wheel Nl upon the base' and engaging said eetli a shaft upon which the gear uutcd7 a drum mounted upon one i., s iafty a friction clutch operatively engaging said drum and having a lever7 the clutcn operating to frictionally engage the druin uponl a movement of theV lever in one dir etion but operatively disenga'ging from the drum upon a movement of t-he lever in the other direction, and frictionally operated means permitting' free upward movement of the standard but locking the standard in a raised position and resisting downward movement thereof.y and manually operable means for gradually releasing the frictional engagement between said frictionally operate-d means and the standard to permit the depression of the standard'.

if; liftiny jacl; of theA cha scribed comprising a tubular ha c ard movable vertically standard having' racl:V th a wheel mounted upon the base and engagingfsaid raclr teetln a shaftw which the gear wheel is mounted? 4 mounted upon'one end of the shaft., a friction clutch operativelyv engaging s Qd drinn and having'a leverqk the clutch operating to frictionally engage the drum upon amovement of the lever in one direction but operativelyv disengaging P movement of the lever iii om the drum upon a in the other direction, a second friction drum tively connected to the said shaft, a frictional brake drum, a lever operabrake band and movable in one direction to contract the brake band upon the drum and in the other direction to expand the brake band upon the drum, means normally urging the brake lever into a position to contract the brake band on the drum, and manually operable means adjustable in one direction to shift the brake lever to thereby reduce the frictional engagement between the brake band and the drum and in the other direction to permit the brake band to frictionally engage the drum.

3. A lifting jack of the character described comprising a tubular base, a toothed standard mounted for vertical movement in the base, a gear and engaging the standard, a shaft on which the gear wheel is mounted and extending laterally outward beyond the base, friction drums mounted upon opposite ends of the shaft, a band formed of two sections embracing one of said drums7 one end of the band extending beyond the other end, a lever having pivotal engagement with the opposite ends of the band, said lever when forced downward contracting the band around the drum and when lifted releasing the grip of the band on the drum, a stop limiting the upward movement of the lever with the drum, a brake band surrounding the other drum and formed of two sections together partially embracing the drum, one end of said brake band extending beyond the other end, a brake lever pivoted to the free ends of the brake band and pivoted to the base carried upon band surrounding the at the end opposite the brake band, a springv urging the brake lever in a direction to contract the brake band upon the drum, and manually operable means on the base for shifting the brake lever in a direction to eX- pand the brake band and reduce the friction between it and the drum.

4. A lifting jack of -the character described comprising a tubular base, a toothed standard mounted for vertical movement in the base, a gear wheel mounted upon the base and engaging the standard, a shaft on which the gear wheel is mounted and eX- tending laterally outward beyond the base, friction drums mounted upon opposite ends of the shaft, a band formed of two sections wheel mounted upon the base` embracing one of said drums, one end of the band extending beyond the other end,A a lever having pivotal engagement to the opposite ends of the band, said lever when forced downward contracting the band around the drum and when lifted releasing the grip of the band on thedrum, a stop limiting the upward movement 0f the lever a brake band surrounding the other drum and formed of two sections together partially embracing the drum, one end of said brake band extending beyond the other end, a lever pivoted to opposite ends of the brake band and pivoted to the base at the end opposite the brake band, a spring urging said lever in a direction to contract the brake band upon the drum, and a cam pivotally mounted upon the base and having a handle,

the cam when turned in one direction bear- Y ing against the lever and urging it in a direction to expand the brake band and when turned in the other direction permitting the brake band to contract around the drum.

5. A lifting jack of the character described comprising a base, a standard vertically movable upon the base, a shaft operatively engaged with the standard, a drum mounted upon tion clutch operatively engaging said drum and having a lever, the clutch operating to frictionally engage the drum upon a movement of the lever in one direction but operatively disengaging it from=` the drum upon a movement of the lever in the other direcf tion, frictionally operated means permitting free upward movement of the standard but locking the standard. in a raised position and resisting downward movement thereof, manually operable means for gradually releasing the frictional engagement between said frictionally operated means and the standard to permit depression of the standard, and a stop carried upon the base against which the lever bears when the lever has been raised to a predetermined extent, said stop preventing the further rotation of the friction clutch and lever with the corresponding drum and .acting as a fulcrumf.

whereby the lever may be turned to open the clutch and permit the downward movement of the standard.

In testimony whereof I hereunto affix my signature. l

THOMAS R. HOLLAND.

one end of the shaft, a fricy 

